mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-21 07:09:15 +07:00
02ab823fd1
This patch makes two additions to the dm path selector interface for
dynamic load balancers:
o a new hook, start_io()
o a new parameter 'nr_bytes' to select_path()/start_io()/end_io()
to pass the size of the I/O
start_io() is called when a target driver actually submits I/O
to the selected path.
Path selectors can use it to start accounting of the I/O.
(e.g. counting the number of in-flight I/Os.)
The start_io hook is based on the patch posted by Stefan Bader:
https://www.redhat.com/archives/dm-devel/2005-October/msg00050.html
nr_bytes, the size of the I/O, is so path selectors can take the
size of the I/O into account when deciding which path to use.
dm-service-time uses it to estimate service time, for example.
(Added the nr_bytes member to dm_mpath_io instead of using existing
details.bi_size, since request-based dm patch deletes it.)
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
98 lines
2.5 KiB
C
98 lines
2.5 KiB
C
/*
|
|
* Copyright (C) 2003 Sistina Software.
|
|
* Copyright (C) 2004 Red Hat, Inc. All rights reserved.
|
|
*
|
|
* Module Author: Heinz Mauelshagen
|
|
*
|
|
* This file is released under the GPL.
|
|
*
|
|
* Path-Selector registration.
|
|
*/
|
|
|
|
#ifndef DM_PATH_SELECTOR_H
|
|
#define DM_PATH_SELECTOR_H
|
|
|
|
#include <linux/device-mapper.h>
|
|
|
|
#include "dm-mpath.h"
|
|
|
|
/*
|
|
* We provide an abstraction for the code that chooses which path
|
|
* to send some io down.
|
|
*/
|
|
struct path_selector_type;
|
|
struct path_selector {
|
|
struct path_selector_type *type;
|
|
void *context;
|
|
};
|
|
|
|
/* Information about a path selector type */
|
|
struct path_selector_type {
|
|
char *name;
|
|
struct module *module;
|
|
|
|
unsigned int table_args;
|
|
unsigned int info_args;
|
|
|
|
/*
|
|
* Constructs a path selector object, takes custom arguments
|
|
*/
|
|
int (*create) (struct path_selector *ps, unsigned argc, char **argv);
|
|
void (*destroy) (struct path_selector *ps);
|
|
|
|
/*
|
|
* Add an opaque path object, along with some selector specific
|
|
* path args (eg, path priority).
|
|
*/
|
|
int (*add_path) (struct path_selector *ps, struct dm_path *path,
|
|
int argc, char **argv, char **error);
|
|
|
|
/*
|
|
* Chooses a path for this io, if no paths are available then
|
|
* NULL will be returned.
|
|
*
|
|
* repeat_count is the number of times to use the path before
|
|
* calling the function again. 0 means don't call it again unless
|
|
* the path fails.
|
|
*/
|
|
struct dm_path *(*select_path) (struct path_selector *ps,
|
|
unsigned *repeat_count,
|
|
size_t nr_bytes);
|
|
|
|
/*
|
|
* Notify the selector that a path has failed.
|
|
*/
|
|
void (*fail_path) (struct path_selector *ps, struct dm_path *p);
|
|
|
|
/*
|
|
* Ask selector to reinstate a path.
|
|
*/
|
|
int (*reinstate_path) (struct path_selector *ps, struct dm_path *p);
|
|
|
|
/*
|
|
* Table content based on parameters added in ps_add_path_fn
|
|
* or path selector status
|
|
*/
|
|
int (*status) (struct path_selector *ps, struct dm_path *path,
|
|
status_type_t type, char *result, unsigned int maxlen);
|
|
|
|
int (*start_io) (struct path_selector *ps, struct dm_path *path,
|
|
size_t nr_bytes);
|
|
int (*end_io) (struct path_selector *ps, struct dm_path *path,
|
|
size_t nr_bytes);
|
|
};
|
|
|
|
/* Register a path selector */
|
|
int dm_register_path_selector(struct path_selector_type *type);
|
|
|
|
/* Unregister a path selector */
|
|
int dm_unregister_path_selector(struct path_selector_type *type);
|
|
|
|
/* Returns a registered path selector type */
|
|
struct path_selector_type *dm_get_path_selector(const char *name);
|
|
|
|
/* Releases a path selector */
|
|
void dm_put_path_selector(struct path_selector_type *pst);
|
|
|
|
#endif
|